add testenv.sh script for setting path
git-pcp.sh in workable state

This commit splits the parallel cherry-pick logic into its own
command, git-pcp.sh
Set git-core path in testenv.sh

testenv.sh has been updated to conditionally set the path to the
installed git-core folder, so that ". git-sh-setup" will work
git-ppr.sh in progress

git-ppr.sh splits out the parallel pull request creation. This standalone tool:

* checks that hub exists and that the github credentials are available

* can use --prefix to derive source and destination branch mappings

* can use --target_branch=source_branch:dest_branch as a way to
  specify branch mapping pairs

* validates the specified github repositories and branches

The actual logic hasn't been amended to work yet, so this tool isn't
yet usable.
pruning junk from git-ppr, fleshing out logic

I think git-ppr.sh should work now, but I'm too tired to test it.
Fix git-ppr auth, PR description logic

Auth credentials from .config/hub weren't being suffixed with x-oauth-basic

pr_msg_dir wasn't being used to source PR description text.
get rid of "[^" bashism, fix infinite look with git checkout failure
Add hub check to git-pcp, cherry-pick from PR

This commit adds more hub-dependent features to git-pcp and splits out
some common requirements into a support file. It also adds support for
$GITHUB_HOST

* git-require-hub.sh encapsulates the GITHUB_URL resolution and hub
  executable requirements

* git-pcp.sh now supports cherry-picking from a pull request - github
  PR URLs can be included in the list of commits alongside standard
  git-style commit refs

* git-ppr.sh has been updated to use the git-require-hub
Create git-cppr.sh to wrap pcp and ppr

git-cppr.sh automates the entire parallel cherry-pick->pull request
process.

* Need to review "action" logic, haven't amended it yet

* Testing needs to happen
cppr works under ideal conditions, ppr fixed

* git-ppr.sh was mixing up source and dest branches, and in fixing
  that I introduced a fork bomb (fixed now)

* git-cppr.sh had some minor syntax and logical errors
remove --skip, tweak --abort for cppr
whitespace fixes
Clean up grammar and unused code, revert stupidity

* Various cleanup

* Previous fix for ppr was actually a break - cppr was feeding
  source:dest branches to ppr incorrectly. Fixed cppr and reverted
  related ppr code.
Docs update, PR description filespec fix

After my last commit, cppr was still putting the generated pull
request descriptions in the wrong file
(.git/cppr_state/pr_desc/dest:source instead of .../source:dest)

* Added minimal testing instructions to README.md
Merge remote-tracking branch 'origin/split_fxnality'

Conflicts:
	cppr.sh
Pull in modularized cppr implementation